Asteroid 2025 FA22 will safely pass Earth on 18 September 2025 at 07:41 UTC (09:41 CEST). It is between 130 and 290 m across and at its closest point to our planet, it will be just over twice as far away as the Moon.
2025 FA22 was discovered using the Pan-STARRS 2 telescope in March this year. Initial observations indicated a small probability that it could impact Earth in 2089. This impact probability, when combined with its relatively large size, saw the object briefly rise to the very top of ESA’s Risk List. However, high-priority follow-up observations soon allowed astronomers to refine the asteroid’s trajectory and rule out any impact risk. The object was removed from the ESA Risk List in May.
While the asteroid poses no risk, it does offer an opportunity. In recent years, the International Asteroid Warning Network (IAWN) has carried out a number of observation campaigns focussed on interesting asteroids, and 2025 FA22 has been selected as the subject of one.
The goal of the IAWN 2025 FA22 campaign is for the global planetary defence community to test its ability to measure the orbit and physical characteristics of a large asteroid passing relatively close to Earth, and to coordinate collaboration and information sharing amongst its members.
The campaign is now underway and will run until the end of October, with ESA’s Near-Earth Object Coordination Centre playing an active role. ESA’s Maxime Devogele is leading the ‘polarimetry’ working group while other members of the team are participating in the ‘astrometry’ working group.
Astrometry refers to the measurement of an object’s position, motion and brightness. Asteroid polarimetry, on the other hand, is a remote sensing technique that studies the polarisation of sunlight scattered by an asteroid’s surface. This information is used to determine the asteroid’s physical properties, such as surface texture, composition and albedo.
While 2025 FA22 poses no danger, practicing out ability to measure these properties is important, as they influence how an asteroid will react to any attempt to deflect it off of a collision course with Earth.
Find out more about asteroids and ESA’s Planetary Defence activities.